Kennedy was still studying his record. “This,”
he remarked slowly, “is what I call my psychophysical
test for falsehood. Lying, when it is practiced
by an expert, is not easily detected by the most careful
scrutiny of the liar’s appearance and manner.

“However, successful means have been developed
for the detection of falsehood by the study of experimental
psychology. Walter, I think you will recall the
test I used once, the psychophysical factor of the
character and rapidity of the mental process known
as the association of ideas?”

I nodded acquiescence.

“Well,” he resumed, “in criminal
jurisprudence, I find an even more simple and more
subjective test which has been recently devised.
Professor Stoerring of Bonn has found out that feelings
of pleasure and pain produce well-defined changes in
respiration. Similar effects are produced by
lying, according to the famous Professor Benussi of
Graz.

“These effects are unerring, unequivocal.
The utterance of a false statement increases respiration;
of a true statement decreases. The importance
and scope of these discoveries are obvious.”

Craig was figuring rapidly on a piece of paper.
“This is a certain and objective criterion,”
he continued as he figured, “between truth and
falsehood. Even when a clever liar endeavors to
escape detection by breathing irregularly, it is likely
to fail, for Benussi has investigated and found that
voluntary changes in respiration don’t alter
the result. You see, the quotient obtained by
dividing the time of inspiration by the time of expiration
gives me the result.”

He looked up suddenly. “Armstrong, you
are telling the truth about some things—­downright
lies about others. You are a drug fiend—­
but I will be lenient with you, for one reason.
Contrary to everything that I would have expected,
you are really trying to save that poor half-witted
girl whom you love from the terrible habit that has
gripped you. That is why you held out the quarter
of the one hundred tablets. That is why you wrote
the note to Mrs. Sutphen, hoping that she might be
treated in some institution.”

Kennedy paused as a look of incredulity passed over
Armstrong’s face.

“Another thing you said was true,” added
Kennedy. “You can get all the heroin you
want. Armstrong, you will put the address of that
place on the outside of the note, or both you and Whitecap
go to jail. Snowbird will be left to her own
devices—­she can get all the ‘snow,’
as some of you fiends call it, that she wants from
those who might exploit her.”